Engine with synchronised free opposed pistons



June '1, 1948. R PESCARA v I 2,442,470 ENGINE WITH SYNCHRONISED FREE OPPOSBD FISTONS Filed July 3, 1945 T7 KT 2 Sheets-Sheet 1 INVENTOR fiaalmeraslbsazm ATTORNEYS June 1, 1948. p, PESCARA 2,442,470

ENGINE wnn smcnnomssn FREE oPPosEn mums Filed July 3, 1945 2 SheetS-Shaot 2 INVENTOR Pazd lbsc'afia ATTORNEYS Patented June 1, 1948 TH SYNCONISED FREE 10 Claims.

My invention relates to engines with synchronised free opposed pistons of the type wherein the piston synchronising device comprises a lazy tongs linkage pivoted about a fixed point.

The chief object or my invention is to provide an engine of this type which is better adapted to meet the requirements of practice than those made up to the present time.

In the annexed drawing:

Fig. 1 is a side view, with parts in section, showing an engine according to my invention.

Fig. 2 is a horizontal longitudinal section thereof taken along line IIII of Fig. 1.

Fig. 3 is an enlarged diagrammatical view to a feature of my invention.

Fig. 4 is an enlarged section taken along line other type of machine, refers to the motor parts 2, the geometrical axis of which is indicated at m'. There is also provided a second cylinder 3, co-axial to cylinder 2 and cooperating with a piston 43 fixed to the outer end of piston l. Piston t, which is larger in diameter than pistons i and la, divides cylinder 3 into two chambers, the inner one 3a being used to compress air for scavenging cylinder 2, while the outer one 3b works as an air cushion to ensure the return stroke of the piston system.

Chamber 3a is provided with an air inlet valve 5 and with an air outlet valve 6 opening into a casing '7 arranged around one end of the motor cylinder 2 and communicating therewith through inlet ports 2a uncovered by piston l atthe end of its outward stroke. The burnt gases and the excess of scavenging air escape through exhaust ports 2b provided toward the opposed end of cylinder 2,

Two longitudinal rods 9 and 9 are fixed to piston 4 in diametrically opposed relation. They are passed through the inner end partition 1a which separates cylinder 3 from casing 1, stufiing boxes or the like being provided to ensure tightness, as it will be described later.

But it could also be an rrossp rrs'roNs Raul Pateras Pescara, Lisbon,

Application July 3, 1945, Serial No.

France August 4, 1942 Portugal (Cl. 123d6) .And each pair of Piston la carries at its outer end a transverse bar lb which is also provided with two longitudinal rods 9a and ee The geometrical axes of rods 9a and 9a are respectively symmetrical of the axes of rods 9 and 9 with respect to the horizontal plane passing through X-X'.

I The inner ends of rods 9, 9 9a and a are The synchronising gearing proper comprises two pairs of lazy tongs scissors oscillatable about the same horizontal axis Y--Y (Fig. 2) which intersects the longitudinal axis X--X' in the vicinity of the central part of the engine, and the two ends of each pair are respectively connected with the ends of a pair 9a, Sa as shown in Fig. 1.

Each pair comprises two oscillating levers. respectively it, it and til it, which are appropriately pivoted about the said transverse axis YY'. The ends of levers it, It and 3 H are articulated with rods, respectively 42, (for lever Ill), 83, 53a (for lever H), 52 Hil (for lever I0 and H3 Rods l2 and i3 are articulated together, as rods Mia and Ba, I2

motion of the pistons, i. e. to the axis of cylinder tioniinner dead point), wh1'le levers ii and H, or levers of the second type, are in a similar position when the pistons are in their outermost position (outer dead point). It will easily be understood that when these conditions are fulfilled, the ratio of the angular motion of levers I0, I0 H, H to the rectilinear motion of the pistons is maximum for respectively one and the other dead points.

Lever H or 1 l is then advantageously used to control the devices or apparatus which are to be outer dead point, such as for instance, a safety device to limit the outward piston strokes, while lever in or I0 controls the devices or apparatus which operate at the inner dead point, for instance the injection pump' and a second safety device adapted to limit the inwar piston strokes.

This may be obtained, ing on shafts l4 and I4 the first type in the first l0, Fig. 2) and a lever of the second type in the as illustrated, by keyrespectively, a lever of of rods 9, 9 and Ha (for lever H pair of lazy tongs (lever second pair of lazy tongs (lever H Fig. 2) shafts i4 and I4 being rotatably supported by the engine casing.

It will be observed that in the construction ill, keyed on shaft I4, is in one piece, rods i2 and Ma parallel therewith, while lever H and rods I3 and Na parallel therewith are in two parts, the whole being symmetrical with respect to a plane parallel to axis X-X'. In the other linkage system lever I loose on shaft I4 and rods l2 and I20, are in two parts, while lever H is in one piece, same as rods I3 Hai the system being also symmetrical with respect to a plane parallel to X-X'. It will easily be understood that these constructive arrangements may be varied at will.

Figs. 1 and 2 diagrammatically show the devices controlled by the synchronising linkage systems through shafts II and I4.

- Shaft It carries a cam Ma which drives two push-rods lid and lBa actuating the fuel injection pump 15 and a safety device It adapted to limit the compression stroke of pistons l and la.

Shaft I4 is similarly provided with a cam Ha driving a push rod l'la. which actuates a second safety device l'l limiting the expansion stroke of pistons I and la.

Fuel pump l5 may be of any convenient construction and it is connected in any appropriate manner with the injection nozzle not shown.

Safety devices l6 and I1 preferably comprise a valve l8 adapted to be pushed by the corresponding push-rod lia or'l'la, whereby a compressed-air chamber l8a (which communicates with a compressed air tank not shown) is connected with a condui I5 is provided with a piston l9 slidable inside a cylinder l9a and conduit l8b opens in cylinder 19a on the inner face of piston I9 (i. e. the face nearer to axis Y-Y') With such an arrangement. when one of devices l6, I1 is operated due to the fact that pistons I and la move beyond their inner or outer safety end limits, compressed air is admitted under piston I9 which is forced outwardly, whereby push-rod lid is disengaged from cam Ha, thus rendering pump l5 inactive.

The outer ends of shafts H and H are advantageously provided with pointers 30 which indicate the piston positions in the vicinity of their inner and outer dead points.

According to a feature of my invention, the synchronizing linkage means, i. e. the.two pairs preferably housed in fluidtight cases 20 and 20 into which rods 9, 9 9a, 9a penetrate through suitable packing means, whereby the synchronising linkage means are insulated from the atmosphere inside casing 1. Cases 20 and 20 are formed by recesses 20a and 2lla (Fig. 2) in the outer engine casing, such recesses being closed by means of covers 2| and 2 l which preferably carry the fuel injection pump and safety devices. Shafts i4 and may be mounted as shown, their outer ends being passed through covers 2| and 21.

Openings 22, 22a, Fig. 1, with stufling boxes or packing glands 23, 23a are provided for the passage of rods 9, 90, etc., such stuffing boxes or acking glands being preferably integral with the afore-described guides 8c. The latter are preferably driven through the corresponding case 20 or 20 and their free end is closed by an appropriate cover.

The openings, such as 22, which correspond to rods attached to piston 4 are connected with the openings provided through partition Ia by means synchronising gearing.

. ates safety of sleeves 24 (Fig. 1) and 24 (Fig. 2). Due to this arrangement each rod needs but one packing gland such as 23 which is preferably disposed in the immediate vicinity of the gearing case. Sleeves 24, 24 are fixed to partition 1a by means of appropriate screwed collars 1b.

This system works in the following manner:

When the outward strokes of pistons l and la reach the maximum values they should have, levers H and H are in positions substantially at right angles to the common axis of the cylinders. For this position of lever H, the spindle I4 which is rigid therewith brings cam a into the position which operates the safety device l1 which is provided for preventing the piston from moving outwardly beyond a given limit position.

When the pistons are close to the ends of their inward strokes, levers ill and I0 are in positions substantially at right angles to the common axis of the cylinders. For this position of lever ill, the spindle H, which is rigid therewith brings cam Ila into the position operating the fuel injection pump. Accessorily, this cam also operdevice l6.

Figs. 3 and 4 show an arrangement adapted to facilitate the mounting and dismounting of the Guides are cylindrical provided with a hole 9d disposed in front of covers 21 and 2 l (supposedly removed in Fig. 3). Holes 9 are adapted to permit of introducing (or removing) a pin 9e by means of and are laterally which slide 9b is simultaneously articulated with the corresponding piston rod 9, 9a. etc., and with the corresponding gearing rod 13, Ba, etc.

The lever gearing may into the corresponding case (Fig. 3) and thereafter extended to bring the free ends of rods l3, Ila, etc., to the proper position to receive the articulation pins lie.

The gearing cases 20, 20 are preferably separated from the motor cylinder 2 by means of a water jacket 25 (Fig.2).

Fig. 5 shows a somewhat modified arrangement wherein the synchronising gearing is disposed unsymmetrically with respect to the transverse plane Z-Z passing through the engine centre. The axis Y-Y of the gearing is slightly displaced toward the admission ports 2a in order to leave more space for the arrangement of the annular exhaust 8. As shown, cases 20 and 20 terminate somewhat beyond ports 2a and the water jacket 25 extends beyond exhaust ports 2b, the annular exhaust 8 being disposed around jacket 25 and connected with ports 2b by means of conduits or nozzles 25a.

. It should be borne in mind that the above description is only given by way of example and does not limit my invention the ambit of which is defined by the following claims.

I claim:

1. A machine of the type described which comprises, in combination, a cylinder, a pair of pistons freely movable in said cylinder, lazy tongs linkage means for synchronising the movements of said pistons, said linkage means including two levers pivoted with respect to each other and to said cylinder about an axis intersecting the cylinder axis perpendicularly thereto, and two auxfor influencing said pistons are dead points, respectively.

2. A machine of the type described which comprises, in combination. a cylinder, a pair of pistons freely movable in said cylinder, lazy tongs easily be introduced linkage means for synchronising the movements of said pistons, said linkage means including two levers pivoted with respect to each other and to said cylinder about an axis intersecting the cylinder axis perpendicularly thereto, a safety device for limiting the outward movements of said pistons operative by one of said levers when said pistons are near the ends of their maximum outward strokes, and a fuel injection-pump operative by the other lever when said pistons are near the ends of their maximum inward strokes.

3. A machine of the typedescribed which come prises, in combination, a cylinder, a pair of pistons freely movable in said cylinder, lazy tongs linkage means for synchronising the movements of said pistons, said linkage means including two levers pivoted with respect to each other and to said cylinder about an axis intersecting the cylinder axis perpendicularly thereto, a safety device for limiting the outward movements of said pistons operative by one of said levers when said pistons are near the ends of their maximum outward strokes, a fuel injection pump and a safety device for limiting the inward movements of said pistons both said pump and said last mentioned device being operative by the other lever when said pistons are near the ends of their maximum inward strokes.

4. A machine of the type described which comprises, in combination, a cylinder, a pair of pistons freely movable in said cylinder, lazy tongs linkage means for synchronising the movements of said pistons, said linkage means including two levers pivoted with respect to each other and to said cylinder about an axis intersecting the cylinder axis perpendicularly thereto so that. one of said levers is perpendicular to said cylinder axis when said pistons are near the ends of their maximum outward strokes and the other lever is perpendicular to said cylinder axis when said pistons are near the ends of their maximum inward strokes, a safety device for limiting the outward movements of said pistons operative by said first mentioned lever when the latter is perpendicular to the cylinder axis, and a fuel injection pump operative by the other lever when the lat-- ter is perpendicular to said cylinder axis.

5. A machine of the type described which comprises, in combination, a cylinder having inlet and exhaust ports, a pair of pistons freely movable in said cylinder, lazy tongs linkage means for synchronising the movements of said pistons, said linkage means includin two levers pivoted with respect to each other and to said cylinder about an axis, nearer to said inlet port than to said exhaust port, intersecting the cylinder axis perpendicularly thereto, and two auxiliary devices operative by said levers respectively for infi-uencing the working of said engine when said pistons are close to their outer and inner dead points, respectively.

6. A machine of the type described whichcomprises, in combinatio a motor cylinder, a pair of pistons freely movable in said cylinder, a reservoir of compressed air for feeding and scavenging said cylinder, said reservoir surrounding said cylinder, means for synchronising the movements of said pistons including at least one oscillating part pivoted with respect to said cylinder and longitudinal rods rigid with said pistons operatively connected with salt. part for actuating it, fluidtight means for insulating said parts from the inside of said reservo and packing means for the passage of said rods through said fluldtight means.

7. A machine of the type described which comprises, in combination, a motor cylinder, a pair of pistons freely movable in said cylinder, 8. reservoir of compressed air for feeding and scavenging said cylinder, said reservoir surrounding said cylinder, means for synchronising the movements of said pistons including at least one oscillating part pivoted with respect to said cylinder and longitudinal rods rigid with said pistons operatively connected with said part for actuating it, means forming a fiuidtight chamber inside said reservoir around said part so as to insulate it from the inside of said reservoir, and packing means in the walls of said chamber for the passage of said rods therethrough.

8. A machine of the type described which comprises, in combination, a motor cylinder, a pair of pistons freely movable in said cylinder, a casing surrounding said cylinder, forming a reservoir of compressed air for feeding andscavenging said cylinder, means for synchronising the movements of said pistons including at least one oscillating part pivoted with respect to said motor cylinder, near the middle part of said machine, and longitudinal rods rigid with said pistons operatively connected with said part for actuating it. means forming a fluidtight chamber (inside said reservoir around said part so as to insulate it from the inside of said reservoir, and packing means in the walls of said chamber for the passage of said rods therethrough.

9. A machine according to claim 8 in which the means forming said chamber consist of the combination of arecessed portion of said casing and a cover.

10.'A machine of the type described which comprises, in combination, a motor cylinder, a pair of pistons freely movable in said cylinder, a casing surrounding said cylinder, forming a reservoir of compressed air for feeding and scavenging said cylinder and a compressor cylinder, a compressor piston slidable in said compressor cylinder and rigid with one of said above mentioned pistons, means for synchronising the movements of said pistons including at least one oscillating part pivoted with respect to said motor cylinder and longitudinal rods rigid with said pis. tons eperatively connected with said part for actuating it, one of said rods being directly fixed to said compressor piston, means for forming a fluidtight chamber inside said reservoir around said part so as to insulate it from the inside or said reservoir, a sleeve directly interposed between said chamber and said compressor cylinder, adapted to accommodate the rod fixed to said compressor piston, packing means between said sleeve and said last mentioned rod, and packing means carried by one wall of said chamber for fluidtight passage of the other rod therethrough.

RAUL PATERAS PESCARA.

REFERENCES CITED The following references are of record in the 

